title: [Contact investigation using QuantiFERON-TB Gold test to evaluate TB exposure in 61 subjects in a hospital setting--(2) Change in QuantiFERON response during one year after exposure].
abstract: OBJECTIVES & SUBJECTS: The change in IGRA (interferon-gamma release assay, with QuantiFERON-TB Gold, QFT) responses was followed up for one year in a group of contacts of healthcare workers who had been exposed to tuberculosis (TB) infection for a relatively short period in a hospital. The observation was made of a total of 59 close contacts of the index case, where 16 showed positive QFT-conversion and 7 showed the intermediate response ranging 0.1 to 0.35 IU/mL. Three of the conversion cases developed active TB.
  
  
  RESULTS
  67% of the QFT conversions occurred within 2 months of exposure and the others between 2 to 9 months. Those having converted later than 2 months after the exposure showed generally weaker QFT responses than the earlier converters. In response to the treatment to converters (either to latent TB infection or to active TB), 80% of the cases reversed to negative or intermediate. The geometric means of the response values for ESAT-6 and CFP-10 also showed significant decline over the treatment time.
  
  
  CONCLUSIONS
  The time profile of responses in the intermediate responders revealed an obviously distinct pattern from that of the negative responders with the values remaining uniformly at very low level throughout, which suggests that this group includes somehow exceptional responders either with or without infection.
authors.affiliation: Division of Laboratory, Tokyo Metropolitan Health and Medical Treatment Corporation, Bokutou Hospital, 4-23-15, Koutoubashi, Sumida-ku, Tokyo 130-8575, Japan. h-kazama27@nifty.com
authors.forename: Haruko
authors.initials: H
authors.lastname: Kazama
authors.forename: Hiroko
authors.initials: H
authors.lastname: Nigorikawa
authors.forename: Machiko
authors.initials: M
authors.lastname: Kashiwa
authors.forename: Shigeko
authors.initials: S
authors.lastname: Miyokawa
authors.forename: Michiko
authors.initials: M
authors.lastname: Tanaka
authors.forename: Masahiko
authors.initials: M
authors.lastname: Ichioka
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Harada
authors.forename: Toru
authors.initials: T
authors.lastname: Mori
mesh_terms: D000328:Adult; D016358:Contact Tracing / Q000379:methods*; D003428:Cross Infection / Q000453:epidemiology* / Q000635:transmission*; D004196:Disease Outbreaks; D005260:Female; D006761:Hospitals / Q000706:statistics & numerical data*; D006801:Humans; D059425:Interferon-gamma Release Tests / Q000379:methods* / Q000706:statistics & numerical data*; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D016273:Occupational Exposure / Q000009:adverse effects* / Q000706:statistics & numerical data*; D013997:Time Factors; D014376:Tuberculosis / Q000453:epidemiology* / Q000635:transmission*; D055815:Young Adult